Nanometer-scale growth of cone cells tracked in living human eye

Humans see color thanks to cone cells, specialized light-sensing neurons located in the retina along the inner surface of the eyeball. The actual light-sensing section of these cells is called the outer segment, which is made up of a series of stacked discs, each about 30 nanometers (billionths of a meter) thick.

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Nanometer-scale growth of cone cells tracked in living human eye